Add StructType for bottom type (Union{})

[quinnj]

Fixes #89.

[codecov]

Codecov Report

Base: 72.86% // Head: 72.68% // Decreases project coverage by -0.18% ⚠️

Coverage data is based on head (a4c170b) compared to base (82b1aa5).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
- Coverage   72.86%   72.68%   -0.19%     
==========================================
  Files           2        2              
  Lines         387      388       +1     
==========================================
  Hits          282      282              
- Misses        105      106       +1     

Impacted Files	Coverage Δ
src/StructTypes.jl	72.14% <100.00%> (-0.20%)	⬇️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[mrufsvold]

Hi! Would you release a version of StructTypes including this update? I opened #89 ages ago, but I forgot to follow up (thanks for fixing so fast btw!). I just bumped up against this issue again today and realized that this fix isn't in the current version of StructTypes.